PROJECT SUMMARY/ABSTRACT The United States opioid crisis, referring to the rapid increase in the 2010s of both prescription and non-prescription opioid abuse in the United States, is a major public health issue, with overdose deaths from opioids reaching epidemic levels, surpassing the number of gun-related deaths in 2016. While heroin remains the main illicit opioid abused in the U.S., a recent dramatic increase in the availability of synthetic opioids (mainly fentanyl and fentanyl-like substances) up to 10,000 times more potent than morphine has placed first responders at risk of accidental overdose and even death. The extreme potency of these substances, which can be accidentally ingested, inhaled, or absorbed through the skin or via contact with mucous membranes, means that accidental contact with even a minuscule amount can pose a severe threat to first responders. Responders can be exposed to fentanyl not only when responding to overdoses, but also during the execution of search or arrest warrants and during the processing of drug or contaminated non-drug evidence. There is a clear need in the community for products to train first responders on how to effectively protect themselves while still performing their duties and providing timely and appropriate care. The computer-based Preventing Opioid Exposure Training (POET) will be an innovative learning product that teaches first responders about the risks of opioid exposures and how to recognize and manage these risks on the job. Training participants will learn to identify warning signs that they may be encountering a potential fentanyl exposure based on the signs and symptoms of a patient and/or the material observed at a scene. Then, the training will review risk assessment and selection of personal protective equipment (PPE) and guidelines for post-exposure treatment, clean-up, and decontamination. For Phase I, the training curriculum will be developed based on exposure guidelines published by federal agencies and other institutions, as well as interviews with stakeholders. This will be followed by usability testing of the prototype as well as a pre- and post-assessment of first responder knowledge gains at the end of training and three months later. This will contribute to shifting the paradigm of how novel training technologies can drive responder preparedness by using virtual worlds to teach first responders how to recognize and manage occupational risks. The potential commercial application of the POET application includes law enforcement officers at the local, state, and federal level, medical professionals (including EMTs, paramedics, and hospital staff), and other responders who face occupational opioid exposure risks.